It looks set to go down in the annals of literary feuds as the Redtop Rogue versus the Gnome. Piers Morgan, former editor of the Daily Mirror, has spilled secrets of the Blairs, Princess Diana and Paul McCartney in his diary, but he may have picked one fight too many by taking on Ian Hislop, the television satirist and Private Eye editor he mocks as a 'Gnome' and a 'moon-faced little midget'.

Morgan's book, The Insider, has been the talk of the political and media classes after its serialisation in a national newspaper last week under the banner 'Confessions of a Redtop Rogue'. Many have condemned it as overcooked trivia, but few have been able to resist looking themselves up in the index, and gossips are still finding some tasty morsels in its 484 pages of scurrilous revelations and confessions.

Morgan's entry for 26 March 1997, for example, catches Tony Blair using some strong language to describe Michael Howard: 'Blair was still seething. "What Howard said about the IRA today was fucking disgusting, frankly, just completely outrageous. Nobody is more determined than me to defeat terrorism, and I'm not going to have him behaving in this reprehensible way." I was a bit shocked - I hadn't heard him swear before.'

On 3 June 2003 Morgan is advising Prince William to 'close down' Paul Burrell - Diana's butler, who was falsely accused of stealing gifts - 'before you regret it'. Morgan tells the future King: '"Oh, come off it, William... Paul feels very aggrieved by the way he's been treated. Why have none of you bothered to contact him and just say sorry, or see how he is?" William looked suddenly very serious. "I have wanted to, several times, but I am not allowed to."'

While the royals and ministers have remained tight-lipped, other 'victims' of Morgan's indiscretions last night hit back, with Hislop - a team captain on BBC 1's Have I Got News for You - in the vanguard.

His feud with Morgan deepened in 2002 when the Mirror launched a campaign offering readers £50 for any scandal on the 'moon-faced little midget'. When Hislop came to Canary Wharf - where the Mirror is based - to sign copies of the Private Eye annual, Morgan scrambled 20 staff to confront him, armed with placards that read: 'Gnome, go home'.

Morgan's entry for 8 November 2002 runs: 'The Hislop campaign has been going well, with all sorts of accusations ranging from a weird obsession with tangerines to a chronic piles problem that needed lasering... I'm just doing it for fun. He is, after all, the editor of a piss-taking magazine and the presenter of a piss-taking TV show. Yet nobody dares take the piss out of him.

'Spencer [Morgan's son] was in the same class at school as Hislop's son William for a couple of years, and I was thus able to observe at first hand what a sly little sod Hislop is. He'd be all friendly to my face, then dump all over me behind my back and in his rag.'

Last night Hislop scornfully rejected the charge and returned fire of his own. 'It's all rather pathetic really,' he said. 'He launched the campaign out of pure personal pique. He made a fool of himself on Have I Got News For You, which he was very embarrassed about. He was furious that we had written about, in particular, the share dealing [Morgan was accused but cleared of abusing his position to profit from shares]. So he is touchy about his personal life, which is fairly extraordinary coming from a man who edited the News of the World .

'He does this thing about: "Ooh, these people, they can dish it out but they can't take it." But I can take it. The man who can't is Piers, who devoted huge resources at the Mirror and doorstepped me, had journalists in my village and went on Friends Reunited [website] to find everyone I've ever met. It wasn't fun, it wasn't a laugh, it was a very expensive and vindictive campaign to try and deflect criticism of himself. I think he thought he could get the Eye to stop writing about him. And it didn't work. "The mountains, being in labour, bringing forth the ridiculous mouse."'

Others named in the book joined in the trashing party. Fiona Millar, partner of Alastair Campbell and former aide to Cherie Blair, said: 'He's obviously got an awful lot of money for this book and is expected to deliver. I don't suppose anybody's going to go through with a fine toothcomb and get the things he said that aren't true rebutted.' Matthew Freud, the public relations consultant, said: 'The standards of journalism on the Mirror were no better. It's Piers. When cartoon characters write books, what do you expect?'

Even Morgan's former deputy editor, Des Kelly, remarked: 'I'm sure his book will do well, and will be right up there with his other great works of literature: the history of Take That and the biography of Philip Schofield.'

Morgan responded last night: 'Je ne regrette rien. The book's sole intention was to entertain the public. Being lectured on accuracy and spinning by Ian Hislop or Fiona Millar has got to be one of the more laughable things I've ever been asked to address.'